Currently SDH/SONET is the major transmission technique
and network application concentrates on IP service
so how to transfer IP data over SDH/SONET becomes an important issue. Based on the discussion over conventional solutions such as PoA (IP over ATM over SDH/SONET) and PoS (IP over SDH/SONET)
this paper makes a analysis on two updated techniques
SDL (Simple Data Link) Protocol and GFP (Generic Framing Protocol)
then points out the advantages and short comings of various protocols.